New, Fast Numerical Algorithm for Diffusion Modeling Implemented in ATHENA Version 5.0

Fast Diffusion Module

A new diffusion algorithm based on a Galerkin method with linear finite elements, an extremely fast sparse matrix solver, and object oriented physical modeling is one of the new features implemented in ATHENA version 5.0. This module is an alternative to the existing code, thus providing the user with a choice between using the old diffusion module and the new algorithms.

The Implicit Linear Finite Element Method (ILFEM) module is available for diffusion and oxidation steps. Switching between the two modules is done using a method statement in the input file, giving the user a flexible choice between numerics for each individual diffusion run.